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1.
Am J Pathol ; 186(2): 324-36, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26683665

RESUMEN

The mammalian target of rapamycin complex 1 (mTORC1) inhibitor rapamycin and its analogs are being increasingly used in solid-organ transplantation. A commonly reported side effect is male subfertility to infertility, yet the precise mechanisms of mTOR interference with male fertility remain obscure. With the use of a conditional mouse genetic approach we demonstrate that deficiency of mTORC1 in the epithelial derivatives of the Wolffian duct is sufficient to cause male infertility. Analysis of spermatozoa from Raptor fl/fl*KspCre mice revealed an overall decreased motility pattern. Both epididymis and seminal vesicles displayed extensive organ regression with increasing age. Histologic and ultrastructural analyses demonstrated increased amounts of destroyed and absorbed spermatozoa in different segments of the epididymis. Mechanistically, genetic and pharmacologic mTORC1 inhibition was associated with an impaired cellular metabolism and a disturbed protein secretion of epididymal epithelial cells. Collectively, our data highlight the role of mTORC1 to preserve the function of the epididymis, ductus deferens, and the seminal vesicles. We thus reveal unexpected new insights into the frequently observed mTORC1 inhibitor side effect of male infertility in transplant recipients.


Asunto(s)
Proliferación Celular/efectos de los fármacos , Fertilidad/efectos de los fármacos , Complejos Multiproteicos/efectos de los fármacos , Vesículas Seminales/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Sirolimus/farmacología , Serina-Treonina Quinasas TOR/efectos de los fármacos , Animales , Masculino , Mamíferos , Diana Mecanicista del Complejo 1 de la Rapamicina , Ratones Transgénicos , Fosforilación , Vesículas Seminales/metabolismo , Factores de Transcripción/metabolismo
2.
Biol Reprod ; 89(3): 59, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23843239

RESUMEN

Uropathogenic Escherichia coli (UPEC)-associated epididymitis is commonly diagnosed in outpatient settings. Although the infection can be successfully cleared using antimicrobial medications, 40% of patients unexplainably show persistent impaired semen parameters even after treatment. Our aim was to investigate whether pathogenic UPEC and its associated virulence factor hemolysin (hlyA) perturb the structural and functional integrity of both the epididymis and sperm, actions that may be responsible for the observed impairment and possibly a reduction of fertilization capabilities. Semen collected from patients diagnosed with E. coli-only related epididymitis showed that sperm counts were low 14 days postantimicrobial treatment regardless of hlyA status. At Day 84 following treatment, hlyA production correlated with approximately 4-fold lower sperm concentrations than in men with hlyA-negative strains. In vivo experiments with the hlyA-producing UPEC CFT073 strain in a murine epididymitis model showed that just 3 days postinfection, structural damage to the epididymis (epithelial damage, leukocyte infiltration, and edema formation) was present. This was more severe in UPEC CFT073 compared to nonpathogenic E. coli (NPEC 470) infection. Moreover, pathogenic UPEC strains prematurely activated the acrosome in vivo and in vitro. Raman microspectroscopy revealed that UPEC CFT073 undermined sperm integrity by inducing nuclear DNA damage. Consistent with these observations, the in vitro fertilization capability of hlyA-treated mouse sperm was completely abolished, although sperm were motile. These findings provide new insights into understanding the possible processes underlying clinical manifestations of acute epididymitis.


Asunto(s)
Epididimitis/microbiología , Epididimitis/patología , Infecciones por Escherichia coli/patología , Espermatozoides/microbiología , Espermatozoides/ultraestructura , Infecciones Urinarias/patología , Escherichia coli Uropatógena/patogenicidad , Adulto , Animales , Embrión de Mamíferos/microbiología , Femenino , Humanos , Infertilidad Masculina/microbiología , Infertilidad Masculina/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Análisis de Semen , Adulto Joven
3.
Cell Tissue Res ; 354(2): 623-32, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23873629

RESUMEN

TCam-2 cells are the main in vitro model for investigations into seminomatous tumors. However, despite their widespread use, questions remain regarding the cells' homogeneity and consequently how representative they are of seminomas. We assess the TCam-2 cell line using routine and novel authentication methods to determine its homogeneity, identify any cellular sub-populations and resolve whether any changes could be due to generational differentiation. TCam-2, embryonal carcinoma cells (2102EP) and breast cancer cell (MCF7) lines were assessed using qRT-PCR, immunocytochemistry, flow cytometry and short tandem repeat analyses. Raman maps of individual cells (minimum of 10) and single scan spectra from 200 cells per culture were obtained. TCam-2s displayed the characteristic marker gene expression pattern for seminoma, were uniform in size and granularity and short tandem repeat analysis showed no contamination. However, based only on physical parameters, flowcytometry was unable to differentiate between TCam-2 and 2102EPs. Raman maps of TCam-2s comprised three equally distributed, distinct spectral patterns displaying large intercellular single spectral variation. All other cells showed little variation. Principal component, cluster and local spectral angle analyses indicated that the TCam-2s contained two different types of cells, one of which comprised two subgroups and was similar to some 2102EP cells. Protein expression corroborated the presence of different cells and generational differences. The detailed characterization provided by the Raman spectra, augmented by the routine methods, provide substantiation to the long-held suspicion that TCam-2 are not homogeneous but comprise differing cell populations, one of which may be embryonal carcinoma in origin.


Asunto(s)
Seminoma/diagnóstico , Espectrometría Raman/métodos , Neoplasias Testiculares/diagnóstico , Neoplasias de la Mama/química , Neoplasias de la Mama/diagnóstico , Neoplasias de la Mama/patología , Línea Celular Tumoral , Femenino , Humanos , Masculino , Seminoma/química , Seminoma/patología , Neoplasias Testiculares/química , Neoplasias Testiculares/patología
4.
Reproduction ; 146(6): R249-58, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-24062567

RESUMEN

At present, evaluation of male reproductive function consists primarily of routine semen analysis, a collection of conventional microscopic assessments ideally performed following the guidelines set by the World Health Organization. While providing some insight into testicular function, these long-performed tests are limited in the information that they impart; more specifically, they are unable to predict true fertility potential. As a consequence, there is a need for the appraisal and consideration of newer semen parameters that may be more indicative of reproductive success. Although various novel assays have been introduced that broaden the scope of information available to both researcher and clinician, the utility of these tests remains limited due to the lack of standardisation of protocols and the absence of clinically established, dependable reference ranges. As such, it is not surprising that most of these parameters and their associated methods remain recommended for 'research purposes only'. With the burgeoning 'omics' revolution, nanotechnology and the development of new analytical instruments, there is now an opportunity for the identification and measurement of previously unknown features that may prove to be more indicative of each sperm's true functional status and capability. Once optimised, simplified, clinically validated and made more readily accessible, these new approaches hold the promise of forming the fulcrum upon which andrological investigations can enter a new era.


Asunto(s)
Necesidades y Demandas de Servicios de Salud , Análisis de Semen/métodos , Análisis de Semen/tendencias , Animales , Antioxidantes/uso terapéutico , ADN/análisis , Genómica/métodos , Necesidades y Demandas de Servicios de Salud/tendencias , Humanos , Infertilidad Masculina/diagnóstico , Infertilidad Masculina/tratamiento farmacológico , Infertilidad Masculina/etiología , Masculino , Estrés Oxidativo/fisiología , Valor Predictivo de las Pruebas
5.
J Assist Reprod Genet ; 29(9): 943-50, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22692281

RESUMEN

PURPOSE: Assess short- and mid-term impact of cryopreservation on DNA methylation status of different genes in spermatozoa. METHODS: Semen samples from 10 healthy normozoospermic men were collected at the Department of Clinical Andrology of the Centre of Reproductive Medicine and Andrology (Muenster, Germany). Each was divided into four equal aliquots: 1) untreated, 2) diluted in cryoprotectant, 3) short term (2 days) cryopreserved and 4) mid term (4 weeks) cryopreserved. Samples were "swim-up" purified prior to analysis. DNA fragmentation was measured using comet assay and Flow cytometric evaluation with Acridine Orange (FCEAO). The degree of methylation of nine genes was determined by bisulfite pyrosequencing of genomic DNA. RESULT(S): Analysis of three maternally imprinted genes (LIT1, SNRPN, MEST), two paternally imprinted genes (MEG3, H19), two repetitive elements (ALU, LINE1), one spermatogenesis-specific gene (VASA) and one gene associated with male infertility (MTHFR) in semen samples demonstrated no alteration in methylation pattern regardless of duration of cryopreservation. CONCLUSION(S): The lack of any changes in the sub-fraction of the genome examined in our study, implies that sperm DNA methylation is unaffected by cryopreservation and suggests that this daily clinical routine is safe in terms of DNA methylation.


Asunto(s)
Criopreservación/métodos , Metilación de ADN , Espermatozoides/citología , Naranja de Acridina/química , Elementos Alu , Ensayo Cometa , Criopreservación/normas , Crioprotectores/química , ARN Helicasas DEAD-box/genética , Fragmentación del ADN , Citometría de Flujo , Genoma Humano , Impresión Genómica , Humanos , Infertilidad Masculina/genética , Masculino , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Canales de Potasio con Entrada de Voltaje/genética , Reproducibilidad de los Resultados , Análisis de Semen/métodos , Sensibilidad y Especificidad , Recuento de Espermatozoides , Factores de Tiempo
6.
Reproduction ; 142(1): 63-71, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21464116

RESUMEN

The synergistic effect of the co-morbidities that comprise metabolic syndrome (MetS) is increasingly being recognised as an important contributor in the pathology of a broad spectrum of seemingly disparate conditions. However, in terms of male reproductive function, beyond erectile dysfunction, little is known about the influence of this cohort (collectively or separately) on spermatogenesis and sperm quality. The aims of this study were to assess the reproductive tract of a MetS animal model for detrimental changes, to determine whether a group of compounds (advanced glycation end products and their receptor) known to cause cell dysfunction and DNA damage was present and assess whether hypogonadotropic hypogonadism was the main contributing factor for the changes seen. Animals fed a high-fat diet were found to have significantly increased cholesterol, triglycerides, blood glucose, mean arterial pressure and visceral fat levels. Although serum testosterone was decreased, no changes were seen in either testicular or epididymal histology. Immunolocalisation of N(ε)-carboxymethyl-lysine and the receptor for advanced glycation end products was found in the testes, epididymides and sperm of the two treated groups of animals; however, ELISA did not show any difference in protein levels. Similarly, assessment of sperm nuclear DNA (nDNA) fragmentation by acridine orange test did not find significant differences in nDNA integrity. We conclude that the minimal effect on spermatogenesis and sperm quality seen in our model is probably due to the moderate increase of blood glucose rather than the hypogonadism.


Asunto(s)
Modelos Animales de Enfermedad , Hipogonadismo/etiología , Síndrome Metabólico/fisiopatología , Espermatogénesis , Espermatozoides/metabolismo , Espermatozoides/patología , Animales , Fragmentación del ADN , Grasas de la Dieta/efectos adversos , Epidídimo/metabolismo , Epidídimo/patología , Productos Finales de Glicación Avanzada/metabolismo , Hormona Liberadora de Gonadotropina/análogos & derivados , Hiperglucemia/etiología , Hipogonadismo/inducido químicamente , Lisina/análogos & derivados , Lisina/metabolismo , Masculino , Síndrome Metabólico/sangre , Síndrome Metabólico/metabolismo , Síndrome Metabólico/patología , Conejos , Distribución Aleatoria , Receptor para Productos Finales de Glicación Avanzada , Receptores Inmunológicos/metabolismo , Análisis de Semen , Espermatozoides/efectos de los fármacos , Testículo/metabolismo , Testículo/patología , Pamoato de Triptorelina/toxicidad
7.
Reprod Biomed Online ; 22(2): 215-9, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21227754

RESUMEN

The long-held view that diabetes has little effect on male reproductive function has been challenged by findings that the condition influences fertility in numerous previously undetected ways. This retrospective chart review of 3000 couples determined the incidence of couples with a male diabetic seeking assisted reproduction treatment and assessed any relationship between male diabetes and IVF/intracytoplasmic sperm injection (ICSI) outcome. Eight (2.7%) couples were found with a diabetic male partner, of which 18 couples underwent assisted reproduction treatment (five IVF, 12 ICSI, one both), with fertilization rates (IVF 68%, ICSI 62%) similar to non-diabetic patients (IVF 70%, ICSI 71%) and no difference in embryo quality. Two men had retrograde ejaculation and two were azoospermic. Other than reduced sperm motility, the remaining 14 had normal World Health Organization semen parameters. Embryo transfers produced one pregnancy (5% combined IVF/ICSI pregnancy rate/cycle) giving a lower-than-expected rate (28.8%). The pregnancy rate from seven FETs (29%) was comparable to the expected (21.3%). Compared with non-diabetics, approximately three times more couples with diabetic men sought treatment, with a larger percentage having 'unexplained' infertility. Fertilization rates and embryo quality did not differ but pregnancy rates were lower in couples with a diabetic male.


Asunto(s)
Complicaciones de la Diabetes/terapia , Fertilización In Vitro , Infertilidad Masculina/terapia , Complicaciones de la Diabetes/epidemiología , Femenino , Humanos , Infertilidad Masculina/complicaciones , Masculino , Embarazo , Índice de Embarazo , Estudios Retrospectivos , Resultado del Tratamiento
9.
Hum Reprod Update ; 20(3): 403-14, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24144514

RESUMEN

BACKGROUND The last 20 years have seen an enormous upsurge in the number of publications reporting findings obtained by Raman spectroscopy, a non-invasive, non-destructive method which uses the inelastic scattering of light to provide a 'fingerprint' of the sample's chemical composition and constituents. Long neglected because of practical difficulties, the technique has been transformed by recent technological advances into a powerful analytical tool capable of opening avenues of investigation that were previously out of the reach of biomedical scientists. Beyond introducing the approach and describing its relative merits and weaknesses, the aim of this review is to provide a spur for discussion of what may become an invaluable tool for biomedical investigations. METHODS A comprehensive review of the literature was conducted searching PubMed and Ovid databases using numerous MeSH terms associated with reproductive medicine. Furthermore, the reference lists of all reported literature were explored. The searches were restricted to English language articles published in the last 50 years. RESULTS Beginning with simple characterizations of biologically and medically important substances, aided by increasing technological sophistication, the use of Raman spectroscopy in biomedicine has quickly expanded to the investigation of complex biochemical interactions, the assessment of organelles and now the evaluation of living cells and tissue. The first Raman investigations of reproductive organs were primarily oncological in nature; however, the past few years have seen an increase in the application of the technique for the assessment and evaluation of both male and female gametes. In particular, progress has been made in the characterization, identification and localization of sperm nuclear DNA damage. CONCLUSIONS The use of Raman spectroscopy has already provided many tantalizing glimpses into the potential that the technique has to answer many of the unresolved issues in investigative and therapeutic reproductive medicine. However, without stringent assessment and the clear representation of the methods' findings, their true meaning cannot be revealed nor should any conclusions be hastily derived. For the potential of Raman microspectroscopy to be truly realized, the dependability and reliability of the technique and its results can only be ascertained by multidisciplinary collaborations that undertake carefully conducted, controlled and analysed studies.


Asunto(s)
Medicina Reproductiva/métodos , Espectrometría Raman/métodos , ADN/análisis , Daño del ADN , Femenino , Humanos , Infertilidad/diagnóstico , Masculino , Reproducibilidad de los Resultados , Análisis de Semen/métodos , Espermatozoides/química , Neoplasias Urogenitales/diagnóstico
10.
Eur J Endocrinol ; 170(4): K11-7, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24394723

RESUMEN

CONTEXT: Classical congenital adrenal hyperplasia (CAH), a genetic disorder characterized by 21-hydroxylase deficiency, impairs male fertility, if insufficiently treated. PATIENT: A 30-year-old male was referred to our clinic for endocrine and fertility assessment after undergoing unilateral orchiectomy for a suspected testicular tumor. Histopathological evaluation of the removed testis revealed atrophy and testicular adrenal rest tumors (TARTs) and raised the suspicion of underlying CAH. The remaining testis was also atrophic (5 ml) with minor TARTs. Serum 17-hydroxyprogesterone levels were elevated, cortisol levels were at the lower limit of normal range, and gonadotropins at prepubertal levels, but serum testosterone levels were within the normal adult range. Semen analysis revealed azoospermia. CAH was confirmed by a homozygous mutation g.655A/C>G (IVS2-13A/C>G) in CYP21A2. Hydrocortisone (24 mg/m(2)) administered to suppress ACTH and adrenal androgen overproduction unmasked deficient testicular testosterone production. As azoospermia persisted due to sustained hypogonadotropic hypogonadism, a combined s.c. gonadotropin replacement with human chorionic gonadotropin (hCG) (1500 IU twice weekly) and FSH (human menopausal gondadotropin (hMG) 150 IU three times weekly) was initiated. RESULTS: Normalization of testosterone levels and a stable low sperm concentration (0.5 mill/ml) with good sperm motility (85% A+B progressive) were achieved within 21 months of treatment. Despite persisting TARTs, while receiving treatment, the patient successfully impregnated his wife twice, the latter impregnation leading to the birth of a healthy girl. CONCLUSIONS: TARTs in unrecognized (simple virilizing) CAH may lead to unnecessary orchiectomy. In hypogonadotropic, azoospermic CAH, a combined treatment with oral corticosteroids and subcutaneously administered hCG and FSH can successfully restore testicular testosterone production and fertility, even if only one hypoplastic and atrophic testis with adrenal rest tumors is present.


Asunto(s)
Hiperplasia Suprarrenal Congénita/complicaciones , Tumor de Resto Suprarrenal/cirugía , Azoospermia/tratamiento farmacológico , Gonadotropina Coriónica/uso terapéutico , Terapia de Reemplazo de Hormonas/métodos , Menotropinas/uso terapéutico , Sustancias para el Control de la Reproducción/uso terapéutico , Neoplasias Testiculares/cirugía , Tumor de Resto Suprarrenal/complicaciones , Adulto , Azoospermia/etiología , Humanos , Hipogonadismo , Masculino , Orquiectomía , Neoplasias Testiculares/complicaciones
11.
Fertil Steril ; 98(3): 611-616.e4, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22633256

RESUMEN

OBJECTIVE: To gauge the performance of laboratories and impact of the German semen analysis external quality control program (QuaDeGA) over its first 10 years. DESIGN: Retrospective analysis of QuaDeGA's twice yearly distribution of fixed semen samples and electronic material documenting sperm motility. Ranking of each participant's responses was determined according to their relation to a "target window." SETTING: Multicenter. PAITENT(S): Healthy donors. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Laboratory performance, World Health Organization (WHO) adherence. RESULT(S): Over 19 runs, there was a steady increase of participants (280 laboratories), the largest group being private urologic practices. Although use of WHO-recommended Neubauer chamber (from 33% to 55%) and diluent (from 11% to 32%) increased, the opposite occurred with morphology staining protocols (from 41% to 19%). Overall, <8% of laboratories truly followed WHO guidelines. Median-based comparisons, replacing reference laboratories, resulted in a merging of performance rankings regardless of the protocols used. CONCLUSION(S): Adherence to WHO recommendations is low, with the majority of laboratories using methods expressly opposed by the guidelines. Participation in QuaDeGA was found to improve the performance of the laboratories involved in the program. However, the use of median-based ranking, while decreasing the extent of variance between laboratories, brings into question the significance of the rankings.


Asunto(s)
Control de Calidad , Análisis de Semen/normas , Adhesión a Directriz , Humanos , Masculino , Estudios Retrospectivos , Recuento de Espermatozoides , Organización Mundial de la Salud
12.
Fertil Steril ; 98(5): 1124-9.e1-3, 2012 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-22835447

RESUMEN

OBJECTIVE: To determine whether Raman microspectroscopy can identify different levels of oxidative sperm nDNA damage and to corroborate the findings using an established method and an alternative but complementary spectroscopic technique. DESIGN: Three-way comparison of Raman profiles, Fourier transform infrared spectroscopy (FTIR) spectra, and flow-cytometric assessments of sperm nDNA damage. SETTING: University-based research laboratory. PATIENT(S): Thirty-eight men attending the infertility clinic at the Centre of Reproductive Medicine and Andrology. INTERVENTION(S): Induction of oxidative damage by Fenton's reaction on semen samples. MAIN OUTCOME MEASURE(S): Raman profiles, FTIR spectra, and flow-cytometric analysis of DNA fragmentation. RESULT(S): Raman and FTIR spectra contained distinctive differences between untreated and fragmented nDNA sperm that were indicative of oxidative attack. The changes in Raman profiles were similar to those previously seen and corresponded to the DNA backbone. The peak attributions were corroborated by the FTIR spectra. Principal component analysis of the entire Raman spectra distinguished samples with varying degrees of damage. After determination of a cutoff value (0.63), estimation of the percentage of sperm with nDNA damage using the intensity ratio of Raman peaks (1,050/1,095 cm(-1)) correlated linearly to the flow-cytometric assessment. CONCLUSION(S): Raman microspectroscopy still requires further validation but may potentially provide a means of assessing the nDNA status of a living sperm.


Asunto(s)
Daño del ADN , ADN/análisis , Infertilidad Masculina/diagnóstico , Microespectrofotometría , Estrés Oxidativo , Análisis de Semen/métodos , Espectrometría Raman , Espermatozoides/química , Biomarcadores/análisis , Citometría de Flujo , Humanos , Peróxido de Hidrógeno , Infertilidad Masculina/genética , Infertilidad Masculina/patología , Hierro , Modelos Lineales , Masculino , Oxidación-Reducción , Valor Predictivo de las Pruebas , Análisis de Componente Principal , Reproducibilidad de los Resultados , Espectroscopía Infrarroja por Transformada de Fourier , Espermatozoides/patología
13.
Fertil Steril ; 92(6): 2085-7, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19589518

RESUMEN

Routine semen analysis found no differences in diabetic men; however, mRNA profiles showed changes in the expression of genes involved in oxidative stress.


Asunto(s)
Diabetes Mellitus Tipo 1/genética , Perfilación de la Expresión Génica , Infertilidad Masculina/genética , Estrés Oxidativo/genética , Espermatogénesis/genética , Fertilidad/genética , Humanos , Masculino , ARN Mensajero/metabolismo , Espermatozoides/fisiología
14.
Hum Reprod ; 22(8): 2169-77, 2007 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-17588956

RESUMEN

BACKGROUND: Diabetics have a significantly higher percentage of sperm with nuclear DNA (nDNA) fragmentation and increased levels of advanced glycation end products (AGEs), in their testis, epididymis and sperm. As the receptor for AGEs (RAGE) is important to oxidative stress and cell dysfunction, we hypothesise, that it may be involved in sperm nDNA damage. METHODS: Immunohistochemistry was performed to determine the presence of RAGE in the human testis and epididymis. A comparison of the receptor's incidence and localization on sperm from 10 diabetic and 11 non-diabetic men was conducted by blind semi-quantitative assessment of the immunostaining. Enzyme-linked immunosorbent assay analysis ascertained RAGE levels in seminal plasma and sperm from 21 diabetic and 31 non-diabetic subjects. Dual labelling immunolocalization was employed to evaluate RAGE's precise location on the sperm head. RESULTS: RAGE was found throughout the testis, caput epididymis, particularly the principle cells apical region, and on sperm acrosomes. The number of sperm displaying RAGE and the overall protein amount found in sperm and seminal plasma were significantly higher in samples from diabetic men (P < 0.01, P < 0.0001 and P < 0.0001, respectively). CONCLUSIONS: The presence of RAGE implies that it may play a central role in sperm nDNA damage particularly in diabetic men where the levels are elevated.


Asunto(s)
Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Epidídimo/química , Receptores Inmunológicos/análisis , Semen/química , Testículo/química , Adolescente , Adulto , Ensayo de Inmunoadsorción Enzimática , Productos Finales de Glicación Avanzada , Humanos , Masculino , Persona de Mediana Edad , Receptor para Productos Finales de Glicación Avanzada
15.
Am J Physiol Endocrinol Metab ; 285(2): E363-71, 2003 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-12721153

RESUMEN

The mechanisms by which excessive glucocorticoids cause muscular atrophy remain unclear. We previously demonstrated that dexamethasone increases the expression of myostatin, a negative regulator of skeletal muscle mass, in vitro. In the present study, we tested the hypothesis that dexamethasone-induced muscle loss is associated with increased myostatin expression in vivo. Daily administration (60, 600, 1,200 micro g/kg body wt) of dexamethasone for 5 days resulted in rapid, dose-dependent loss of body weight (-4.0, -13.4, -17.2%, respectively, P < 0.05 for each comparison), and muscle atrophy (6.3, 15.0, 16.6% below controls, respectively). These changes were associated with dose-dependent, marked induction of intramuscular myostatin mRNA (66.3, 450, 527.6% increase above controls, P < 0.05 for each comparison) and protein expression (0.0, 260.5, 318.4% increase above controls, P < 0.05). We found that the effect of dexamethasone on body weight and muscle loss and upregulation of intramuscular myostatin expression was time dependent. When dexamethasone treatment (600 micro g. kg-1. day-1) was extended from 5 to 10 days, the rate of body weight loss was markedly reduced to approximately 2% within this extended period. The concentrations of intramuscular myosin heavy chain type II in dexamethasone-treated rats were significantly lower (-43% after 5-day treatment, -14% after 10-day treatment) than their respective corresponding controls. The intramuscular myostatin concentration in rats treated with dexamethasone for 10 days returned to basal level. Concurrent treatment with RU-486 blocked dexamethasone-induced myostatin expression and significantly attenuated body loss and muscle atrophy. We propose that dexamethasone-induced muscle loss is mediated, at least in part, by the upregulation of myostatin expression through a glucocorticoid receptor-mediated pathway.


Asunto(s)
Glucocorticoides/efectos adversos , Músculo Esquelético/química , Atrofia Muscular/inducido químicamente , Factor de Crecimiento Transformador beta/genética , Animales , Peso Corporal/efectos de los fármacos , Dexametasona/efectos adversos , Dexametasona/antagonistas & inhibidores , Dexametasona/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Cinética , Masculino , Mifepristona/farmacología , Músculo Esquelético/patología , Miostatina , Tamaño de los Órganos/efectos de los fármacos , ARN Mensajero/análisis , Ratas , Ratas Sprague-Dawley , Receptores de Glucocorticoides/fisiología
16.
J Cell Physiol ; 190(2): 170-9, 2002 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11807821

RESUMEN

Myostatin is a negative regulator of skeletal muscle growth. We have previously reported that recombinant myostatin protein inhibits DNA and protein synthesis in C2C12 cells. Our objective was to assess if C2C12 cells express myostatin, determine its sub-cellular localization and the developmental stage of C2C12 cells in which myostatin mRNA and protein are expressed. To study the endogenous expression of myostatin, C2C12 myoblasts were allowed to progress to myotubes, and changes in the levels of endogenous myostatin mRNA expression were determined by RT-PCR. The myostatin protein and the two major myosin heavy chain (MHC) isoforms (MHC-I and -II) were determined by Western blot. Confirmation of the relative MHC expression patterns was obtained by a modified polyacrylamide gel electropheretic (PAGE) procedure. Imunofluorescence staining was employed to localize the site of myostatin expression and the relative distribution of the MHC isoforms. Co-expression of these proteins was studied using a dual staining approach. Expression of myostatin mRNA was found in myotubes but not in myoblasts. Myostatin protein was seen in most but not all, of the nuclei of polynucleated fibers expressing MHC-II, and myostatin was detected in the cytoplasm of myotube. The localization of myostatin protein in myotube nuclei was confirmed by Western blot of isolated nuclear and cytoplasmic fractions. Incubation of C2C12 myotubes with graded doses of dexamethasone dose-dependently increased the intensity of nuclear myostatin immunostaining and also resulted in the appearance of cytoplasmic expression. In conclusion, myostatin was expressed mostly in C2C12 myotubes nuclei expressing MHC-II. Its predominant nuclear localization suggests that it may play a role in transcriptional regulation.


Asunto(s)
Músculo Esquelético/metabolismo , Cadenas Pesadas de Miosina/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Animales , Northern Blotting , Western Blotting , Línea Celular , Núcleo Celular/metabolismo , Dexametasona/farmacología , Glucocorticoides/farmacología , Antígenos de Histocompatibilidad Clase II/metabolismo , Inmunohistoquímica , Ratones , Ratones Endogámicos C3H , Músculo Esquelético/citología , Músculo Esquelético/efectos de los fármacos , Miostatina , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Coloración y Etiquetado , Fracciones Subcelulares/metabolismo , Distribución Tisular , Factor de Crecimiento Transformador beta/genética
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